1. Field of the Invention
The present invention relates to a fan assembly, more particularly to a fan assembly which is provided with lubricant-containing bearings so as to prolong the service life thereof.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional fan assembly is shown to include a mounting member 11, a stator 12, a rotor 13, and a tubular bearing 122. The mounting member 11 defines an axially extending bore 112, and includes an annular mounting plate 111 disposed in the bore 112, a plurality of ribs 113 extending radially and outwardly from the mounting plate 111 to connect with a bore-defining wall surface that confines the bore 112 so as to form a plurality of ventilation holes 112xe2x80x3, and a mounting tube 115 that extends axially from the mounting plate 111 and that has an inner wall surface to confine a bearing-receiving space. The stator 12 is sleeved securely on the mounting tube 115, and has a plurality of coils 123. The rotor 13 includes a generally U-shaped rotor casing 131, a rotor shaft 134, and a plurality of blades 133. The rotor casing 131 is disposed in the bore 123, and surrounds the stator 12. The rotor shaft 134 extends axially from the rotor casing 131, and is inserted rotatably and co-axially into the bearing-receiving space of the mounting tube 115. The blades 133 extend radially and outwardly from the rotor casing 131. A magnetic sleeve 132 is disposed within the rotor casing 131 around the stator 12. A tubular bearing 122 is disposed in the bearing-receiving space of the mounting tube 115, and is sleeved on the rotor shaft 134. A C-shaped fastener clip 135 is mounted on the rotor shaft 134 to prevent disengagement of the rotor 13 relative to the stator 12.
Some disadvantages resulting from the use of the aforementioned conventional fan assembly are as follows:
(1) The service life of the conventional fan assembly is short, because the lubricant disposed in the tubular bearing 122 gradually diminishes since no covering means is provided to prevent loss of the lubricant.
(2) Provision of such covering means results in increased manufacturing costs.
(3) Since the entire inner wall surface of the bearing 122 slidably contacts the rotor shaft 134, the force of friction therebetween is relatively large.
Therefore, the object of this invention is to provide a fan assembly with lubricant-containing bearings of a simple construction so as to eliminate the aforesaid disadvantages of the prior art.
Accordingly, a fan assembly according to the present invention includes: a mounting frame, a stator, a rotor, first and second bearings, and first and second annular bearing-covering caps. The mounting frame includes a mounting plate, and a hollow mounting tube extending transversely from the mounting plate. The mounting tube has an inner wall surface confining a bearing-receiving space, and an annular flange that projects inwardly and radially from the inner wall surface into the bearing-receiving space, and that has two opposite sides and two opposite annular side faces. The stator is sleeved securely on the mounting tube. The rotor includes an annular rotor casing, a rotor shaft, and a plurality of blades. The rotor casing surrounds the stator. The rotor shaft extends axially from the rotor casing, and is inserted rotatably into the mounting tube. The blades extend radially and outwardly from the rotor casing. The first and second bearings are respectively disposed at the opposite sides of the annular flange within the bearing-receiving space in the mounting tube, and are sleeved on the rotor shaft. Each of the first and second bearings has a U-shaped cross section, an annular abutment plate that abuts against a respective one of the annular side faces of the annular flanges of the mounting tube, and a peripheral flange that extends axially from the abutment plate, that slidably contacts the inner wall surface of the mounting tube, and that cooperates with the rotor shaft and the abutment plate to define a lubricant-receiving reservoir thereamong. The first and second annular bearing-covering caps are snugly fitted into the bearing-receiving space in the mounting tube, are sleeved on the rotor shaft, and respectively and sealingly cover the lubricant-receiving reservoirs in the first and second bearings.